The Outsider (2018)

In 1954, nine years after the pacific war, Nick Lowell is the only non-Japanese inmate in an Osaka prison. Most of his fellow inmates are yakuza criminals, recognizable by their irezumi tattoos. Nick saves a yakuza named Kiyoshi from being hanged to death; the Shiromatsu, a yakuza clan to which Kiyoshi belongs, repays his debt by arranging Nick's release.